As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
An information handling system may include a Serial ATA Interface as a storage interface. Serial ATA was developed as a replacement for Parallel ATA as a storage interface for desktop and portable computer systems. The Serial ATA Interface offers a number of advantages over the Parallel ATA Interface, including a reduction in signaling voltages and required pin count, an elimination of a cable length limitation, and improved data robustness. To this time, however, the Serial ATA standard does not provide for external cabling. As such, for external storage systems, another interface, such as SCSI, must be used for the connection between the host adapter and the external storage subsystem.
An external storage subsystem may be configured to include, for example, a host adapter in a server that is coupled via a SCSI connection to a JBOD (just a bunch of drives) enclosure. Current solutions with either Parallel ATA drives or Serial ATA drives in a JBOD enclosure poorly emulate the use of SCSI drives in a JBOD. In the case of Parallel ATA drives in a JBOD, the entire enclosure of Parallel ATA drives is instantiated as one or two SCSI target IDs. Although some bridge devices have been developed that use LUN (logical unit number) identification to map SCSI target IDs to Parallel ATA drives, this solution is likewise problematic in that a typical RAID controller will only recognize the first one to eight LUNs of the JBOD enclosure, even though the SCSI protocol permits a maximum of 64 LUNs per target controller. This configuration, using Parallel ATA drives, may similarly be applied to Serial ATA drives, but does not take advantage of the benefits of the existing SCSI infrastructure of storage management and RAID controllers.
In a JBOD enclosure having Serial ATA drives behind a SCSI target interface, assigning each drive its own SCSI ID may not be an achievable solution with the use of known storage management architectures. Because the target controller of the JBOD enclosure typically responds to only a single SCSI ID, regardless of the number of Serial ATA drives, transparently replacing SCSI drives with Serial ATA drives with the goal of mapping the Serial ATA drives in a JBOD enclosure according to a unique SCSI ID is problematic. Likewise, assigning each Serial ATA drive its own LUN identifier and mapping to each Serial ATA drive on the basis of its LUN identifier would not provide a transparent solution for replacing SCSI drives with Serial ATA drives, as existing RAID controllers and storage management are not configured to map to drives in this manner.